Scientists Avoid Embryos In Creating Stem Cells

Scientists have succeeded in reprogramming ordinary cells from the tips of mouse tails and rewinding their developmental clocks so they are virtually indistinguishable from embryonic stem cells, according to studies released Wednesday.

If the discovery applies to human cells -- and researchers are optimistic that it will -- it would offer a straightforward method for creating a limitless supply of cell lines tailor-made for patients without any ethical strings attached.

Three research groups said they accomplished their feat by activating four genes that are turned on in days-old embryos. Some of the rejuvenated cells grew into new mice, demonstrating the cells' ability to create every type of tissue in the body.

"This is truly the Holy Grail -- to be able to take a few cells from a patient, say a cheek swab or some skin cells, and turn them into stem cells in the laboratory," said Dr. Robert Lanza, an embryonic stem cell researcher and head of scientific development at Advanced Cell Technology Inc. in Worcester, Mass., who was not involved in the research. "It would be like turning lead into gold."

Massachusetts Institute of Technology biologist Rudolf Jaenisch, who worked on two of the studies, said there are still "lots and lots of technical hurdles to overcome." Some of the thorniest problems might take years to resolve despite the fact that mice and humans share many fundamental aspects of cell biology.

But if those hurdles are cleared, reprogrammed cells could become the long-sought substitute for embryonic stem cells, which are at the heart of the nascent field of regenerative medicine.

President Bush and other social conservatives have long opposed human embryonic stem cell research because the cells can be obtained only by destroying embryos. Government funding of such research is a top political issue in Washington on which the House is set to vote today.

Reprogrammed cells could allow scientists to sidestep the ethical dilemmas for therapeutic cloning, in which scientists try to create a human embryo that is genetically identical to a sick patient by inserting the patient's DNA in an unfertilized egg.

The resulting stem cells harvested from the embryo could theoretically be used to generate neurons for patients with Parkinson's disease or insulin-producing cells for diabetics without running the risk of tissue rejection. Stem cells derived from reprogrammed cells also would also eliminate the need to harvest human eggs, a procedure fraught with risk for women donors.

"This would be a win for science, ethics and society," added Richard M. Doerflinger, secretariat for pro-life activities for the U.S. Conference of Catholic Bishops in Washington, D.C. *